Objective To investigate the trajectory of parenting stress among mothers of premature infants within 6-month corrected age and discharged from NICU, and to provide evidence for development of intervention measures to reduce parenting stress for preterm infants′ mothers in the future. Methods Mothers of 356 premature infants discharged from the NICU，were enrolled in the study. The mothers were surveyed with the Parenting Stress Index-short form(PSI-SF), the Center for Epidemiological Studies Depression Scale(CES-D), the Brief Coparenting Relationship Scale(Brief CRS), Social Support Rating Scale(SSRS), Neonatal Medical Index (NMI) at 1 week after infant discharge, corrected gestational age at 1 month, 3 months and 6 months. Results The total score of maternal parenting stress was (100.73±19.11) points, (105.96±21.08) points, (90.71±17.16) points, and (88.22±17.76) points at 1 week after infant discharge, corrected gestational age at 1 month, 3 months and 6 months, respectively. The factors related to mother′s parenting stress were baby′s birth weight, whether the mother has an elder child, mother′s depressive symptoms and the degree of social support（P<0.05,P<0.01）. Conclusion Parenting stress among mothers of premature infants discharged from NICU first sees a climb then decreases gradually. It is suggested that medical staff should formulate intervention strategies according to the influencing factors and carry out targeted parenting support measures as soon as possible to help mothers of premature infants adapt to the role of mother and reduce their parenting stress.